Products and methods for improving animal dental hygiene

ABSTRACT

Products and methods for reducing tartar on the teeth of a pet are provided. In an embodiment, a chewable product that enhances dental hygiene in a pet is provided comprising a body having a continuous phase and a discontinuous phase in such a proportion so that the force required to penetrate the product is greater than an anticipated bite force exerted by the pet during a normal biting event, and below the maximum force that the pet may periodically exert.

This application claims the benefit of Provisional Application No.60/280,064, filed Mar. 30, 2001.

BACKGROUND OF THE INVENTION

The present invention generally relates to dental hygiene. Morespecifically, the present invention relates to improving the dentalhygiene of pets. It relates also a polymer composition having acontinuous phase and a discontinuous phase, and which may findapplication in improving pet dental hygiene.

It is of course known that there are many different products forimproving the health and well-being of animals, especially pets. Theseproducts run a vast array including products designed to improve dentalhygiene in pets.

It is known that poor dental health is very common in animals, includingpets such as dogs and cats. Poor dental hygiene can result inperiodontal disease. Periodontal disease is one of the most commonlytreated disease by veterinarians in the United States.

The long term impact of poor dental health can be devastating to ananimal. Poor dental health is thought to be a contributing factor in thedeaths of dogs, cats, and other manuals. In pets, it has been linkedwith serious diseases of the heart, liver, kidney, and other internalorgans. Indeed, one study demonstrated that every dog with periodontaldisease had pathological changes in the heart, liver, and kidneys.

Most periodontal disease starts with the formation of a film of a softamorphous material called plaque, consisting primarily of oral bacteria,bacterial byproducts, and oral debris. This film typically covers boththe exposed tooth surface and the area lying under the gum line, thegingival cavity. Through the deposition of calcium and other mineralsalts, this layer of plaque hardens and develops into tartar. Althoughtartar is hard, it is also porous and adheres to the tooth surface. Itappears to be progressively deposited in layers and provides a roughsurface onto which more plaque is deposited. As tartar builds up, abroad range of microbes can attach. The byproducts of metabolism fromthese bacteria cause inflammation of local tissues including thosesurrounding the gingival cavity. This ultimately leads to periodontaldisease. The earliest stage is gingivitis, characterized by inflammationof the gums. As periodontal disease progresses, gingivitis becomesperiodontitis, with inflammation extending into the connective tissuessurrounding the tooth. Through gingivitis and periodontitis, it isthought that harmful bacteria enter into the blood stream and ultimatelylodge in the heart and other internal organs.

It has been found that the sides of the teeth facing the cheeks, i.e.located in the buccal cavity, have a greater incidence of gingivitis andplaque/tartar build-up than the sides of the teeth facing the tongue,i.e., the lingual side. It has also been found that the rear teeth,i.e., the pre-molars and molars; more rapidly develop plaque and tartarthan the front teeth.

A variety of development efforts have focused on cleaning teeth andimproving dental hygiene in animals. One simple method for removingplaque in pets is for the pet owner to brush his pet's teeth regularly.Unfortunately, few pet owners are willing or able to maintain this levelof home care.

Therefore, efforts have focused on providing products that clean theteeth of pets while being chewed. There are a number of such productsthat claim to help clean the teeth of pets. However, few are totallyeffective and many suffer from a variety of disadvantages.

One of the problems of such products is that some of them are notedible. Hence, once the products are chewed or broken up by the pets andswallowed they cause digestive problems in the animals. Another problemwith some products is that they have limited efficacy in cleaning themolars and pre-molars. These are the teeth where typically tartar buildup is heaviest and also which are the most difficult teeth for an ownerto clean with a toothbrush.

Further, many such products do not always clean the crevices of theseteeth. Moreover, many such products are ineffective in cleaning theareas underneath the gums. Still further, many such products are noteffective in promoting cleaning of the surfaces of the teeth that arelocated in the rear of the buccal cavity. If the product is poorlydesigned, then, during chewing, little of the product will actuallyenter the rear buccal cavity, thus leading to reduced abrasive actionand limited cleaning of the tooth surface.

A further problem is that many of these products are ineffective inremoving existing tartar. Because tartar is so hard, attempting toremove tartar by the simple abrading action caused by chewing may not beeffective in reducing the tartar.

Some such products have oral care additives that are designed to inhibitthe formation of tartar. A problem with some of these products is thatthey do not necessarily function as desired. In this regard, theefficacy of these agents disappears when the product is swallowed orother food is eaten by the animal. In a similar vein, some of theseproducts are unstable and their texture changes with time, losing theircleansing properties.

U.S. Pat. No. 6,110,521 describes a wheat and casein dog chew having atexture that can be modified by the dog minder by subjecting the chew tomicrowave radiation, causing expansion and rendering it more easy tochew. To enable the expansion under microwave heating, the product hasto have a moisture content of 10% to 14% by weight.

PCT patent publication number WO 00/13521 describes a chewable toy for apet that has a protein based thermoplastic composition and can befashioned into the shape of a bone. Applicants believe that the productsdescribed therein have limited dental efficacy. The application suggeststhat simply producing a product that “mimics natural animal bone shapes”and which allows “pets to softly penetrate the chewable toy” promotesclean healthy teeth and fresh breath. But, such a product will notnecessarily promote effective teeth cleaning, especially in thedifficult areas such the rear teeth, e.g., the molars, under the gumlines and in the area opposite the cheeks, i.e., the buccal cavity.These are the areas where plaque accumulation can rapidly develop intogingivitis and pathogenic bacteria enter the blood stream withpotentially harmful consequences.

European patent application number EP 0 552 897 A1 discloses an edibleanimal chew product with a flexible cellular matrix containingcellulosic fibers e.g. 20 to 50% corn cobs and oral care additives.However, a difficulty with the product of this disclosure is thatcorncob and such cellulosic materials are unnatural to a pet animal'sdiet and can contribute to diarrhea and increased fecal volume. This isthe opposite of the desires of many owners, who prefer not to haveincreased fecal volume from their pets. Another disadvantage of theabove products is that they rely on the teeth being initially cleaned bydental prophylaxis by a veterinarian. Few owners regularly have aveterinarian perform dental prophylaxis.

A common failure of the prior art is that it neglects the bite forceexerted by the teeth and the biting behavior of the target animals. Ifthe bite resistance is too high, then the teeth will not evenlypenetrate the product and there will be little opportunity for theproduct to push against the gums and clean in critical areas.Conversely, if the bite resistance is too low then the dog will rapidlybite through the product and swallow the product. Thus, little pressurewill be exerted against the tooth surface under the gums again leadingto poor cleaning in critical areas.

There is therefore a need for improved products and methods forenhancing the dental hygiene of a pet.

SUMMARY OF THE INVENTION

The present invention provides a polymer composition having a continuousphase and a discontinuous phase, the discontinuous phase beingdistributed within the continuous phase, the said continuous phase beingcomposed of at least one polymer of biological origin or a derivative orcomplex of such polymer.

The present invention further provides improved products for improvingthe dental hygiene of a pet. Additionally, the present inventionprovides improved methods for making products for enhancing the dentalhygiene of a pet.

To this end, in a first aspect of the invention, there is provided achewable product that enhances dental hygiene in a pet. The productcomprises a body having a continuous phase and a discontinuous phase insuch a proportion that the force required to penetrate the product isgreater than an anticipated bite force exerted by a pet in apredetermined target group of pets during a normal biting event.Desirably, in addition, the required penetration force is, however, lessthan the maximum bite force typical of the said target group. Theanticipated bite force is defined to be that of an average pet in thepredetermined target group.

In an embodiment, the continuous phase is composed a polymer ofbiological origin or a derivative or complex thereof. In a furtherembodiment, it may additionally contain smaller solvating molecules,preservatives, anti-oxidants, crystallization retardants, inorganicions, flavour molecules and other smaller compatible molecules and ions.

In an embodiment, the biologically originating polymer is chosen fromthe group consisting of: carbohydrates and/or derivatives ofcarbohydrates including polysaccharides; starches; polydextrans; allpolymers and polysaccharides of or derived from naturally occurringhexose, pentose and heptose sugars and their derivatives;polysaccharides of microbial origin including those derived fromfermentation of the above and below mentioned substances or byfermentation of any food based medium; hydrocolloids; hydrocolloids ofmicrobial origin; hydrocolloids of plant origin; polyols; polyols ofmicrobial origin; sugar alcohols; polymers of sugar alcohols;carbohydrates derived as by-products of or that are the wastes fromhuman food processing; proteins and/or derivatives of proteins includingglycoproteins, lipoproteins, phospho-proteins, tropocollagens, andderivatives/hydrolysates/complexes of tropocollagen; milk proteins andderivatives such as those present in the hydrophobic protein fraction ofmilk e.g. the caseinates; those polymers present in milk solids; milksolids and derivatives; proteins derived from eggs; proteins from orderived from meat and the wastes associated with slaughtering and meatprocessing; proteins derived as by-products of or the wastes from humanfood processing; polypeptides; plant proteins; proteins of microbialorigin; animal proteins; polymers of microbial cell wall origin;polymers of microbial cellular origin; polymers containing a combinationof protein and carbohydrate monomers or that are formed by combiningcarbohydrate and proteinaeous material; polymers containing acombination of lipid and/or protein and/or carbohydrate monomers or thatare formed by combining lipid and/or protein and/or carbohydrateelements to form a new polymer or complex of polymers; all otherpolymers of biological origin or derived from those of biological originthat exhibit the desired functional properties apparent in the abovementioned polymers.

In an embodiment, the discontinuous phase is composed of:micro-occlusions/microscopic particles of all non-reactive/insolubleorganic/biological substances with melting points and/or glasstransition points above room temperature and as well those with meltingand/or glass transition points below room temperature that are notsoluble in the continuous phase, occlusions/particles of allnon-reactive/insoluble organic/biological substances with melting pointsand/or glass transition points above room temperature and as well thosewith melting and/or glass transition points below room temperature thatare not soluble in the continuous phase, non-active inorganic substancesthat are compatible with and do not react or significantly interact withthe substances present in the continuous phase, carbohydrates and/orderivatives of carbohydrates including saccharides, sugars,polysaccharides, ungelatinized starches, starches and/or derivatives,inulin, polyfructans, polydektrans; all polymers of the naturallyoccurring hexose, pentose and heptose sugars and their derivatives,cellulose and polymers derived from cellulose, amino-polysaccharidessuch as chitin, chitosan and polymers derived from these substances,oligiosaccharides, polysaccharides of and derivatives of polysaccharidesof microbial origin, polyols, polyols of microbial origin, sugaralcohols, polymers of sugar alcohols, mineral oxides, inorganic andorganic oxides, phosphates, sulphates, carbonates and other insolublesalts or covalently bonded inorganic substances, polymers of ormixtures/complexes and combinations of all of the aforementionedinorganic: and organic substances, aluminosilicates, silicates,inorganic substances common in soils, clays, minerals, metals andsubstances derived from the metals, bone, cartilage, oils, fats, gases,petroleum derivatives and petroleum based polymers,micro-occlusions/particles of microbial origin, intact non-viablemicrobes, dry intact non-viable microbes, the shells and cell wallmaterial derived from dead microbes, material of microbial origin,micro-occlusions/particles of plant origin, material of plant origin,micro-occlusions/particles of animal origin, material of animal origin;such polymers and substances of biological origin as are also present ascomponents of the continuous phase, being present in the discontinuousphase in a different state to their state in the continuous phase.

In an embodiment, the polymers and substances of biological origin, asare present as components of both the continuous phase and thediscontinuous phase, are present in the discontinuous phasepredominately in the glassy or crystalline state.

In an embodiment, the polymers and substances of biological origin asare also present as components of both the continuous phase and thediscontinuous phase, are present predominately in the rubber state.Preferably, the components common to both states are present in thediscontinuous phase as dispersed, relatively small and discreteparticles.

In an embodiment, the product is in the shape of a bone.

In an embodiment, the product is in the shape of a flat bone.

In an embodiment, the product is in the shape of a flat long rectangularbox or any shape that when drawn fits in such a box and touches each ofthe surfaces of such a box.

In a preferred form of the invention, there is thus provided a productfor cleaning teeth of a pet, the product being chewable and having acontinuous phase and a discontinuous phase in a proportion so that theforce required to penetrate the product is greater than an anticipatedbite force exerted by the pet, and wherein, after an initial bite by thepet, at least a portion of the surface bitten by the pet springs back tosubstantially its original shape.

In a second aspect of the present invention, a method for providingdental hygiene to a pet is provided. The method comprises the steps ofproviding a pet with a chewable product that includes a continuous and adiscontinuous phase and selecting the relationship of the continuous todiscontinuous phase so that the force required to penetrate the productis, greater than an anticipated initial bite force of the pet during anormal biting event, causing the product after an initial bite to springback to at least almost its original shape. The relationship of thephases may be in regard to composition or proportion in the product. Ina preferred form of the invention, the continuous phase is predominantlyin the rubber state and the discontinuous phase is predominantly in thecrystalline or glassy state.

In a further aspect of the present invention, a method for making achewable product for enhancing dental hygiene is provided. The methodcomprises the steps of: producing a chewable, edible product thatincludes a continuous and a discontinuous phase; and selecting therelationship of the continuous to discontinuous phase so that the forcerequired to penetrate the product is greater than an anticipated initialbite force of the pet during a normal biting event, causing the productafter an initial bite to spring back to at least almost its originalshape. In a preferred form of the method of manufacture, the continuousphase is formed in the rubber state.

The invention extends also to a method of maintaining or improving thecondition of a pet, the method including the step of facilitating theremoval of tartar from the pet's teeth so as to improve or maintain theoral health of the pet.

It is an advantage of the present invention to provide a product forimproving the dental health of a pet and thereby its general condition.

Another advantage of the present invention is to provide an improvedmethod for enhancing the dental hygiene of an animal, especially a petsuch as a cat or a dog.

Still further, an advantage of the present invention is to provideimproved methods for removing plaque from the teeth of a pet andinhibiting the buildup of tartar on the teeth.

Additionally, an advantage of the present invention is to provide aproduct that retards tartar buildup on the teeth of pets.

Additional features and advantages of the present invention will bedescribed in and apparent from the detailed description of the presentlypreferred embodiments and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a cross-sectional view of a pet's mouth.

FIG. 2 illustrates a schematic view of tartar on the teeth of a dog asviewed under a scanning electron microscope.

FIG. 3 illustrates a perspective view of an embodiment of a product ofthe present invention.

FIG. 4 illustrates schematically an embodiment of the structure of thepresent invention as viewed under a microscope.

FIG. 5 illustrates schematically an embodiment of an apparatus formaking a product of the present invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The present invention provides a polymer composition having a continuousphase and a discontinuous phase, the discontinuous phase beingdistributed within the continuous phase, the said continuous phase beingcomposed of polymers of biological origin or derivatives or complexes ofsuch polymers. This composition may be applied in the manufacture ofproducts that may be used in health related fields. The invention thusfurther relates generally to products and methods for improving thedental hygiene of a pet, in particular a dog or a cat. In part, theproducts and methods of the present invention are designed to reduceplaque and tartar formation and build-up on the teeth of a pet.

The invention further provides a method of maintaining or improving thehealth of a pet by inhibiting the spread of pathogens, having oralorigin, from the mouth of the pet to other areas of its body, such asits vital organs. Through facilitating the removal of tartar from thepet's teeth, the accumulation, propagation and spread of such pathogensis inhibited. This is expected to have a beneficial effect on thegeneral or overall health and condition of the pet. The method mayinclude the step of administering to the pet a chewable body having acomposition comprised of a continuous phase within which is dispersed adiscontinuous phase. The body is preferably administered at regularintervals to the pet, the intervals being chosen to be sufficientlyshort to inhibit the formation or reformation of tartar on the pet'steeth. For example, the chewable body may be administered daily toprovide an abrasive action when contacted with the pet's teeth, therebyfacilitating tartar removal and inhibiting its regrowth or reformation.

Referring now to FIG. 1, generally the mouth 10 of a pet is illustrated.As illustrated, a typical pet's mouth 10 includes a tooth 12 that islocated, in part, within the gums 14 of the pet. An area between thetooth 12 and gums 14 is defined by the gingival cavity 16.

As set forth above, tartar can form on the teeth 12 of the animal.Tartar can be difficult to remove, especially if it is located in thebuccal cavity 18, the area located between the teeth 12 and the cheek 20of the mouth. Additionally, it is difficult to remove tartar that islocated in the gingival cavity 16. Unfortunately, it is the tartarlocated in the gingival cavity 16 that can be most detrimental to thehealth of a pet.

Referring to FIG. 2, schematically there is illustrated across-sectional view of tartar 30 as viewed under a scanning electronmicroscope. As illustrated, the tartar comprises a number of inorganiclayers 32 and 34 which have sandwiched therebetween proteinaceous layers36 and 38. The inorganic layers 32 and 34 have a hard porous structure.

Referring now to FIG. 3, an embodiment of the product 40 of the presentinvention is illustrated. As illustrated, the product 40 provides anedible chewable product that enhances the dental hygiene of a petanimal. Although the product is illustrated in the shape of a bone, avariety of shapes can be used for product 40, e.g., a biscuit or a flatelongate generally rectangular body or any shape that would fit into animaginary rectangular box and would touch each of the internal surfacesof such a box. Preferably, the corner extremities of the body wouldapproximately generally coincide with the corners of the box.

The product 40 is designed to have a superior cleaning action due to itsresistance to tooth penetration when chewed. To this end, the product 40comprises a body 42 having a continuous phase and discontinuous phase.FIG. 4 illustrates schematically the continuous phase 44 anddiscontinuous phase 46 as viewed under a microscope. The phases 44 and46 are carefully balanced to ensure optimum texture for cleaning of thesurface of a pet's teeth.

The continuous phase 44 is preferably composed of an interlocking matrixof polymers. These polymers are further preferably of biological originand can be derived from many different sources including products of,and by-products from, human food processing and derivatives thereof,animal sources, plant sources, products of and by-products of meatprocessing, products of and by-products common to the baking and cerealprocessing industries and derivatives thereof, milk and milkderivatives, microbial sources and from the microbial modification ofproducts and by-products from the aforementioned sources, as well as abroad range of other well known sources of natural bio-polymers. Thecontinuous phase may also contain smaller solvating molecules,preservatives, anti-oxidants, crystallization retardants, inorganicions, flavour molecules and other smaller compatible molecules and ionsthat do not have a negative impact on polymer interaction. Thesepolymers of biological origin are held together/interact in a dynamicnon-covalent manner by hydrogen bonding, ionic attraction, Van der Waalsinteractions and other forms of non-covalent bonding. This phase willnormally be in a rubber-like state and will preferably pass through aglass transition point well below room temperature. It may also bepreferable to have substances present in the continuous phase that canretard crystallization of the other components of the continuous phase.

In contrast to the continuous phase 44, the discontinuous phase 46consists mainly of non-active (“inert”) or low activity substances thatwill not extensively bind to the components of the continuous phase.However, there will be enough interaction between the phases to ensurethat the discontinuous phase will remain part of the total structure andwill not fall out of the enclosing matrix. The discontinuous phase maybe a mixture of different substances with one or two dominantsubstances. It is possible that the discontinuous phase may even consistof some components of the continuous phase that are in a crystalline orglassy state.

A variety of components can be used for the discontinuous phase andinclude micro-occlusions/particles of virtually allnon-reactive/insoluble organic/biological substances with melting pointsand/or glass transition points above room temperature, as well thosewith melting and/or glass transition points below room temperature thatare not soluble in the continuous phase. Also possible are non-activeinorganic substances such as mineral oxides, phosphates, carbonates andother insoluble salts or covalently bonded inorganic substances ormixtures/complexes and combinations of same.

Examples of substances, from which the discontinuous phase may becomposed are: micro-occlusions/microscopic particles of allnon-reactive/insoluble organic/biological substances with melting pointsand/or glass transition points above room temperature and as well thosewith melting and/or glass transition points below room temperature thatare not soluble in the continuous phrase; occlusions/particles of allnon-reactive/insoluble organic/biological substances with melting pointsand/or glass transition points above room temperature and as well thosewith melting and/or glass transition points below room temperature thatare not soluble in the continuous phase; non-active inorganic substancesthat are compatible with and do not react or significantly interact withthe substances present in the continuous phase; carbohydrates and/orderivatives of carbohydrates including saccharides, sugars,polysaccharides, starches and preferably ungelatinized starches,derivatives of starches, inulin, polyfructans, polydextrans; allpolymers of naturally occurring hexose, pentose and heptose sugars andtheir derivatives; cellulose and polymers derived from cellulose;amino-polysaccharides such as chitin, chitosan and polymers derived fromthese substances; oligosaccharides, polysaccharides of and derivativesof polysaccharides of microbial origin; polyols, including polyols ofmicrobial origin; sugar alcohols, polymers of sugar alcohols, mineraloxides, inorganic and organic oxides, phosphates, sulphates, carbonates;other insoluble salts or covalently bonded inorganic substances;polymers of or mixtures/complexes and combinations of all of theaforementioned inorganic and organic substances; aluminosilicates,silicates, inorganic substances common in soils, clays, minerals, metalsand substances derived from the metals, bone, cartilage, oils, fats,gases, petroleum derivatives and petroleum based polymers;micro-occlusions/particles of microbial origin, intact non-viablemicrobes, dry intact non-viable microbes, the shells and cell wallmaterial derived from dead microbes, material of microbial origin,micro-occlusions/particles of plant origin, material of plant origin,micro-occlusions/particles of animal origin, material of animal origin.Where a polymer in the discontinuous phase is of biological origin andis also found as a component of the continuous phase, it will be presentin the discontinuous phase in a different state to its state in thecontinuous phase. Preferably it will therefore be present in thediscontinuous phase in the glassy or crystalline state. Other polymersthat are present should preferably be predominately in the glassy orcrystalline state. However, there are embodiments in which theaforementioned polymers are predominately in the rubber state, in whichthey will exist as dispersed, relatively small and discrete particles.

It is desirable that, as illustrated, the discontinuous phase 46 at themicroscopic level is relatively evenly dispersed throughout thecontinuous phase 44. This ensures minimum disruption to the continuityof this phase. The ratio of the materials present in the two phases canbe manipulated to vary the resultant product to suit the desiredapplication.

It should be noted that it is possible that at the macroscopic levelthere maybe additional gross occlusions in the product e.g. grains ofcereal etc. These occlusions would be part of the discontinuous phase,but differ from the rest of the discontinuous phase in that theirinterior will possess its own unique combination of phases andmolecules. Hence due to the gross size of the said occlusions, these cansignificantly and independently influence the resultant productcharacteristics. For a dental hygiene product for dogs, the preferredstructure of the product 40 has no gross occlusions, as these couldcause a significant disruption to the continuous phase and anundesirable increase in fragility of the product.

In a preferred embodiment, at least a portion of the polymer of thecontinuous phase is in the rubber state. This state is found to improve“chewability” of the product—i.e. the duration of chewing exhibited by apet dog without the product body disintegrating significantly. In a morepreferred embodiment, the rubber state proportion is in the main. Byincreasing the proportion of the continuous phase that is in the glassstate, a harder product is produced and chew duration is increased.However, care needs to be taken to maintain the proportion that is inthe glassy state at a level below which brittleness is increased to theextent that the product may easily shatter under biting. This would havepotentially negative and even harmful consequences for the pet, forexample by the liberation of sharp fragments. No more than a relativelyminor proportion of the polymer of the continuous state should becrystalline, therefore.

In another preferred embodiment, the continuous phases should be free ofcomponents that interfere with the rubbery character of the biologicalpolymer. Such substances include certain divalent cations. These mayinterfere with the flexible character of the body 40.

In preferred embodiments, the product 40 is composed of approximately20% to about 40% by weight starch, approximately 20% to about 40% byweight protein, and 5% to about 40% of water. In farther preferredembodiments, the product is composed of approximately 20% to 31% byweight starch, 25% to 37% by weight protein and 15% to 20% by weight ofwater. Preferably, the starch acts as the primary component of and isevenly dispersed through the discontinuous phase and the protein acts asthe primary component of the continuous phase.

Regarding phase weight distribution, it is preferred that the continuousphase should make up from about 20% to about 80% of the product weight,further preferably from about 25% to 60% of the total weight.

The product 40 is designed to have a texture suited to the bite forceexpected to exerted by a predetermined target group of pet animals. Thetexture of the material used to construct the product 40 is selected toensure that the force required to penetrate the product is greater thanthe bite force exerted by the teeth of an average animal in the targetgroup of animals during a normal biting event. In a preferredembodiment, however, the required penetration force is still below themaximum bite force typical of the said group of animals. At the sametime, the elastic nature of the material of the product 40 is selectedsuch that, after penetration, the material springs back. This creates asecondary cleaning action after the primary cleaning action experiencedin attempting penetration. This action also helps to push back the edgeof the gums and thus facilitates cleaning of the pet's teeth indifficult to reach areas.

The product is designed to have a durability that ensures that theproduct 40 remains in the mouth of the pet for an extended period oftime. This thereby increases the opportunity for cleaning while theproduct 40 is being chewed. It also provides pet keepers with a readymeans and method of keeping their pet occupied. Unlike prior artproducts, the product 40 will not quickly fracture into pieces that canbe easily swallowed by the dog. Also unlike other prior art products,the product is safer for the pet as it is not hard and does not splinterinto dangerous fragments that can lodge in the animal's throat.

If desired, the product 40 may include other active ingredients, forexample agents that may inhibit the initial formation of tartar. Theproduct 40 may alternatively or in addition comprise chelating and otheragents that help soften tartar, and facilitate tartar's removal whenabraded, such as when the product is chewed. Examples of such activeagents are disclosed in U.S. patent application Ser. No. 60/279,998, thedisclosure of which is incorporated herein by reference.

As noted above, the product 40 can have a variety of sizes and shapes.In a preferred embodiment of the invention that is illustrated, the body42 is of a size and generally bone-like, flat shape that has beenspecially designed to fit easily in between the teeth and cheeks oftargeted dogs. It will be appreciated that the different shapes may bepreferred, depending on the targeted dogs and their mouth structure. Theshape typified above has been found optimum for beagles and other dogswith similar mouth structures. This shape has the advantage that dogsderive great pleasure in holding such a product between their frontpaws, first chewing on one side then on the other. This helps ensureimproved cleaning for all teeth contained in the pet's mouth. Inparticular, the shape encourages the dog to concentrate the chewingaction on the rear teeth, the teeth that are the most difficult to reachwith a toothbrush and where tartar build up can be significant. The sizemay vary, influenced by the size of dog in the target market. Ingeneral, the length to breadth ratio will be in the range from about 2:1to about 4:1. Preferably it will be approximately 3:1. The thicknessshould be generally about a third to a half of the maximum width.

Pursuant to the present invention, the product can have a wide range oftextures. The texture alone is enough to ensure effective teethcleaning. Nonetheless, fibrous and insoluble abrasive elements may bepresent in the product, but are not essential.

The product 40 can be designed to have an optimum chewability for mostdogs. Pet dogs can have very powerful jaws and have been found totypically exert a biting force of between 100 newtons to about 400N witha median of 163N and average force of 256N. The texture of the productof the present invention is selected to ensure that the force requiredto penetrate the product 40 is greater than the bite force exerted bythe teeth of an average dog in the target group of animals during anormal biting event (in other words the median force referred to above),and below the maximum force that a dog may periodically exert.Penetrometry studies showed that on the surface normally bitten, thepreferred embodiments of the product of this invention typicallyrequired a force of approximately 225 newtons for penetration by aspecially constructed “model tooth.” Also, the penetration by this“model tooth” did not fracture the product as often happens with many ofthe more brittle prior art products.

Another surprising observation was that after penetration with and thenwithdrawal of a probe of 4 mm diameter, the hole partially reclosed toless than 2 mm diameter. Hence, when bitten by a dog, the elastic natureof the product 40 ensures that, after penetration, it actually springsback and pushes against the animal's tooth surface, thus ensuringintimate contact with the tooth surface and enhanced mechanicalcleansing action.

The product 40 is very durable with many bites being required before theproduct 40 is of sufficient size to be swallowed. For example, it hasbeen found that it takes between approximately 3.5 to about 12 minutesfor a medium to large dog (having weight in the range from about 10 kgto 35 kg) to consume the product 40. The prolonged chewing that isrequired facilitates increased contact with the teeth and hence theeffectiveness of the mechanical abrasive cleaning action in removingplaque, the precursor for tartar.

The product 40 of the present invention offers a number of benefits.These include: stronger, better quality products; means for inclusion ofdifficult ingredients that may otherwise compromise the product qualityor strength and their delivery to the pet's teeth; cheaper products withobtainable without compromise to desired properties such as strength andflexibility, since decreased amounts of potentially expensive continuousphase material may be used without compromising the essential featuresof the product; and simplicity of production as the systems describedmake use of low pressures and can be combined with well known formingtechnologies.

A variety of methods may be used for manufacturing the product 40. Onemethod includes the steps of mixing ingredient powders and liquids in asystem that can exert, for a desired period and at the appropriate time,controlled mechanical shear and/or temperature to ensure that a desiredtransitory physical state for each phase is reached within theprocessing vessel. These states may be any one or a combination of theglassy, rubber, crystalline or intermediate states. Before it exits fromthe primary vessel, the material is thus processed in such a manner andto such an extent as to ensure that it exits in the main as a carefullybalanced combination of a continuous phase and a discontinuous phase;and that the phases will have all the desirable characteristicsmentioned above and be in the desired aforementioned physical states.

The preferred primary vessel for use in manufacturing the product 40 isan extruder. Preferred extruders are of the long barrel type. Afterleaving the extruder, the resultant material is then manipulated in sucha manner to form a predetermined shape. The shape may be adapted tofacilitate mechanical cleansing of a pet animal's teeth and be able toaccess difficult areas of the animal's mouth. This manipulation of thematerial may also be designed to enhance the desirable aspects of thephysical state of the product 40, for example by promoting a molecularalignment that increases resistance to tooth penetration under the forceof biting. The product 40 is then preferably stored carefully in suchmanner as to ensure that no normally encountered environmental influencecan cause change in the states of its phases.

Since the combination of materials in the product phases have thepotential to be spun, woven, molded and stretched into a film, they alsohave a wide range of other applications outside of pet dental hygiene.For example a common problem in the food and feed industry iscontamination of the food product with metal, plastic and the likenon-edible identity tags. Rendered animal materials are frequentlycontaminated with such metal identity tags that are used foranimal/carcass identification. Tags can be made instead using theprocesses described herein. These animal tags will disappear duringrendering and processing and be totally edible.

Another application of the present invention is with respect to thesurgical implantation of splints or pins to fix broken bones. Currentlysuch products are constructed from metal or plastic. After theirimplantation, a second operation is necessary to remove such pins.Pursuant to the present invention, artificial bones that are initiallysterile, very strong and are slowly broken down by mammalian enzymes canbe provided. The ingredients of the products can be selected to reducethe risk of an immune response, e.g., including a tropocollagenderivative, such as gelatine. Hence these are an attractive alternativeto metal or plastic implants/pins.

Referring again to the dental hygiene pet product 40 of the invention,it is composed principally of water, carbohydrate and protein. Theproduct can be manufactured by a variety of processes involving mixing,cooking and forming. By way of example, and not limitation, thefollowing manufacturing method can be used to manufacture products 40 ofthe present invention:

Referring to FIG. 5, a general embodiment of a manufacturing apparatus50 for making a product of the present invention is illustratedschematically. First, dry ingredients are mixed in a mixer 52.

The dry mixture is added to the extruder 56, together with any desirableliquids 54, for example water, glycerol and oil or fat. The mixture isheated in the extruder 56 to a suitable cooking temperature withsufficient energy being input to cause it to enter a bioplastic state.The degree of heating and extent of cooking may be used as a means ofcontrolling the ultimate density and texture of the resultant product.After cooking in the extruder 56, the product exits the extruder 56 as ahigh-density bioplastic fluid at relatively low temperature (about 75°C.-90° C.) with little expansion taking place at the die orifice 58.

Due to the fluid nature of the extrudate as a bioplastic, it can beeasily formed into a vast range of shapes at low pressure, meaning atatmospheric or close to about atmospheric pressure. Accordingly, it isnot necessary to mold the extrudate under relatively higher pressure, asin for example, injection or compression molding. The extrudate, beingessentially a plastics material, can be readily drawn out into thinfilms, sheets, ropes, balls etc. The extrudate also emerges from theextruder in a microbiologically stable state, i.e., it does not need tobe dried or treated to ensure microbiological safety. The extrudatemerely needs to be cooled to room temperature. Cooling is best donegradually, as it is found that over rapid cooling creates steep thermalgradients and uncontrolled physical states within the product body sothat uneven properties are exhibited. These are undesirable where theylead to stress cracks appearing.

Advantageous extruders for the method of the present invention are thosereferred to as long barrel high-speed twin screw extruders. They havesmaller diameters and much tighter tolerances and work at higher screwspeeds than their predecessors. Hence they can exert much greater torqueunder much better control than older style machines, providing highenergy controlled input that brings the ingredient mixture to abioplastic state and enables it to be maintained for sufficientresidence time and under cooking conditions to facilitate desiredtexturisation. Preferably the ingredients are subjected to a specificmechanical energy of at least about 250 J/g.

The product exits the extruder through a die 58. The product thentravels along conveyor 60.

In an embodiment, the product is then is passed through a biscuit gaugeroller 62 from which emerges a flat sheet of material with veryaccurately controlled thickness and width and improved compressionstrength.

In an embodiment, this sheet again is conveyed along a conveyor 64 andit can be cut, for example with a biscuit rotary cutting apparatus 66,before proceeding to a packing station 68. It will be appreciated thatalternatively, the sheet need not be passed through the roller 62, butmay be sent directly to the cutting apparatus.

One alternative method of cutting is to cut the above mentioned sheetusing a water jet cutter at station 66 in FIG. 5. Water jet cutters aretypically used in the leather goods industry to cut leather sheets toproduce the blanks for making shoes.

Because the material progresses through a broad range of physical statesduring processing—such as powder, rubber, glass, fluid and crystalline—alarge number of forming processes is possible. The state is selected andcontrolled with a view to intended further processing. Other possiblemachines for processing the product include: confectionery equipment forhandling toffees and hard sweets, e.g., depositing machines, chocolatemolding systems, chain drive cutters for toffees, and blow moldingmachines, as the product is blowable into a thin, translucent film.Other possible machines include those typically used the biscuitindustry for forming biscuits e.g. bar presses, wire cutting systems,etc and also those used elsewhere in the human food industry or plasticsindustry e.g. rotary formers etc.

The resultant product of the process set forth in FIG. 5 is resemblesHDPE (high density polyethylene) in that it can easily be carved with aknife or sawn with an industrial jigsaw. However, for pet dentalapplications, it is found that the product should desirably have anon-cellular matrix and be of relatively high density. The preferreddensity range is from about 0.8 to 1.2 g.cm⁻³. At densities that are toolow, there are likely to be gas pockets that will reduce the biteresistance of the product. Excessively high densities will reduceflexibility and penetrability to unacceptable levels for pet dentalapplications.

It is important to note that the products of the invention may beextruded at low moistures compared to standard petfoods. Use of anextruder is desirable, as it can handle such mixtures and quickly bringthem to the optimum temperature. It is thought that after introductionto the extruder, the mixture “melts” and becomes quite fluid.

A variety of products can be constructed pursuant to the presentinvention. For cats and dogs, preferred applications include dentalchews, toys and confectionery. In the case of pet dental hygieneproducts, the Applicants have determined that the best texture for adental hygiene product for dogs is a product with high density and anon-cellular matrix. It has been surprisingly found that it is possibleto extrude these mixtures without any added water or steam. This isunusual as in the food industry almost all extrusion is carried outusing added water, water-based solutions or steam. In the absence ofadded moisture, the inclusion of an humectant provides a degree offlexibility. The humectant may be any suitable humectant, for example,glycerin, propolyne glycol, butylene glycol, polyhydric glycols such asglycerol and sorbitol, hydrogenated starch, hydrolysates and the like.Low levels of water may, however, be included, even if only to act asplasticizer. In preferred embodiments, the sum of water and humectant inthe final product is desirably in the range from about 15% to 45% byweight, but is more preferably from about 25% to 35% by weight.

By way of example, and not limitation, examples of products and methodsof making same will now be given:

EXAMPLE 1

Five separate batches of product samples were made from the fivemixtures of dry ingredients prepared according to the compositions shownin Table 1 and designated “1a” through “1e”. Each batch of ingredientswas in turn charged to a Sovemeca Mixer (Sovemeca Ltd, Vermand, France).

TABLE 1 Sample Number 1a 1b 1c 1d 1e Ingredient name Wt % Wt % Wt % Wt %Wt % SODIUM CASEINATE* 44.0 28.0 36.0 48.0 CORN STARCH 38.82 39.0 48.039.0 LACTIC YEAST 20.0 20.0 EXTRACT POWDER** SODIUM BENTONITE 3.5 MILKPROTEIN CO- 28.0 PRECIPITATE*** BROKEN RICE, 39.0 GROUND GELATIN 10014.0 10.0 8.0 10.0 10.0 BLOOM**** PRESERVATIVE - 0.75 0.7 0.7 0.7 0.7SORBIC ACID NUTRIENT MIXTURE 2.43 2.3 3.8 2.3 2.3 Total 100.00 100.00100.00 100.00 100.00 *Supplied by Sodial Ltd, Montablan, France.**Supplied by Bel Industries, Vêndome, France. ***Supplied by Centre R.& D. Nestlé, Lisieux, France ****Supplied by Dutch Gelatine Ltd.

After mixing, each of the dry mixtures was metered directly into theinlet of a long barrel high-speed twin screw extruder via a K-tron weighbelt. Liquid humectant and plasticiser mixtures, being of water,glycerol and edible oil, were injected via peristaltic pumps, monitoredby flow meters, with quantities being under automatic control by aPLC-based program. Approximately 1 part liquid mix was added to about2.5 parts of solids by weight, the liquid mix comprising about 3 partsglycerol to one part water. After gentle cooking to a temperature ofabout 80° C. and to a pressure of about 4 atmospheres, the materialemerged from the extruder via the die as a thin sheet, at low pressureof about 1.5 atmospheres and a temperature of about 77° C. Afterallowing each of the samples to cool to below about 65° C., all exceptsample 1d were next conveyed on a conveyor directly to a Rotary Biscuitcutter (Sasib Ltd, UK), with which they were cut to shape and size.

After cutting to bone-like shapes, the cut pieces were graduallyair-cooled to room temperature to avoid overstressing the product andpacked into hermetically sealed sachets.

Sample 1d was made as above except that a modified extrusion method wasemployed in that the die used was approximately 1 metre in length andthe product was shaped by cutting the extrudate with a water cutter, ofthe type typically used in the leather industry for fabricating shoes.

Table 2, below, sets forth an analysis of the resultant product samples.

TABLE 2 Composition of manufactured samples 1a 1b 1c 1d 1e Component Wt% Wt % Wt % Wt % Wt % WATER 17 16 15.5 19 16 FAT 0.8 1.1 0.6 1.1 0.8PROTEIN 37 25.1 28.1 22 39.2 STARCH* 21.2 22.0 32 26 20.5 CRUDE FIBRE0.1 4.0 — 3.8 0.1 ASH 2.7 3.5 5.2 — 3.2 GLYCEROL 15.4 14.0 15.8 18 16.5ORGANIC ACIDS 1.2 1.0 0.9 1.1 1.1 Approx. Weight % of 55 30 40 30 50Continuous Phase *estimated

Each of the products had a density of about 1 g.cm⁻³ weight of about 50g and, except for sample 1d, dimensions of length 12.5 cm, width about4.2 cm and thickness about 1.2 cm. Sample 1d had a maximum width ofabout 3.6 cm and thickness of 1.4 cm.

The produce of sample 1a was found to comprise about 55% by weight ofcontinuous phase and about 45% by weight of discontinuous phasematerial. The continuous phase appeared as a matrix with no readilydistinguishable particle structure, as one might observe in the case ofa material having discrete units. It was found to comprise an intimatemixture of caseinate protein and gelatin. The discontinuous phaseappeared as discrete particulate units substantially evenly dispersedthrough out the product body. These were found to be made up ofdistinct, visible particles of ungelatinized starch, distinct particlesof caseinate and gelatin in the crystalline/glass state. Particles ofash, probably emanating from the nutrient mix, and some of the sorbicacid preservative were also noticed as phase discontinuities. Similarobservations were made in respect of the samples 1b through 1e, in whichthe relative phase distributions were influenced by the initialingredient mix for each sample.

The texture of each sample was analyzed with a system designed tosimulate the biting action of a dog's teeth. A TA-XT2I Texture analyser(Rheo Ltd, Champlan, France) was equipped with a specially designedcone-shaped penetrometry probe of length 12 mm, that was pushed slowlyinto the product, descending at a rate of 2 mm/s. Measurements were madeof the force required. Unlike comparable edible pet chew products in themarket, the products of the invention did not break when penetrated. Astandard three point flexion test was also carried out using thismachine. For sample 1a, it showed flexion through 20 mm without breaking(see Table 3 below).

TABLE 3 Texture Analysis: Product Samples 1a-1e Product Penetrationforce* f_(max) Flexion Force f_(max) Flexion Distance Sample (flatsurface) [N] [N] [mm] 1a 225** 242  20** 1b 180**  88  20** 1c 262** 23014 1d  90**  40  40** 1e 245  250 15 (10 mm) *For a 12 mm spindle tofully penetrate product **Never broke

Sample 1d proved highly flexible in relation to the others and was onlymoderately resistant to penetration. Hence it was considered moresuitable for fabrication of products for small dogs known to have areduced bite force.

EXAMPLE NO. 2

Each day, over a period of 21 days, each member of a group (designated“Product 1”) of 12 beagle dogs was individually fed one of the productsmade pursuant to Sample 1a in Example 1 above, in addition to a diet ofa canned commercial pet food. The combined diet of chew product andcanned food was designed to yield approximately 100% of the calculateddaily metabolic energy (ME) requirements of the dog. The single dailychew product of sample 1a provided approximately 25% of the dog's dailyME needs.

A second group (designated “Control 1”) of 12 beagle dogs wassimultaneously fed on only the canned commercial pet food, providing100% of their daily ME requirement. At the end of the period, bothgroups were assessed for the accumulation of tartar on their teeth.

Before commencement of the test, an oral examination had been conductedon each dog prior to selecting it for the trial. Dogs with known orobserved dental/oral problems (e.g. severe periodontal disease,excessive number of missing teeth etc) were not included.

Each dog was put through preliminary screening to check its feedingbehaviour. Prior scoring was done to assess how each of the dogs cheweda standard treat. They were grouped into blocks depending on theirobserved behaviour. The behaviour groupings were very fast chewers,moderate chewers and slow chewers.

Dogs were blocked for assignment to the diets on the basis of this chewscore, age and sex. Diets were assigned randomly within blocks. The dogswere confined indoors to eat. For the group receiving the product, itwas given in a bowl, 4 hours after the main meal, in the morning. Thebowl was removed 1 hour after and the amount of treats not eaten wasscored and measured. Eleven Dogs ate all of the product on every day ofthe test period. The twelfth dog ate its treat only partially on 3 outof 21 days.

Complete dental prophylaxis (ultrasonic cleaning and polishing) wasperformed on all dogs on the first day of the test period. On day 21,the dogs were sedated for a brief period of time (several minutes) toenable an evaluation of tartar buildup to be performed. The teeth werefirst gently brushed with a toothbrush, rinsed with a forced stream ofwater, then air-dried. The tartar was then visually recorded for theproximal, medial and distal thirds of the buccal surfaces of the teeth.The amount of the surface covered with tartar in a particular ⅓ segmentwas scored as 0=no plaque; 1=<25%; 2=25-49%; 3=50-74%; 4=75-100%. Thethickness of the tartar was scored as 1=Light; 2=Moderate; 3=Heavy.Total score for one tooth was achieved by multiplying the thickness andcoverage scores for each segment and summating the resultant values ofthe 3 segments.

The scores for all surfaces for each animal were added and divided bythe number of teeth to provide each animal's individual score. A meangroup score was obtained by averaging the scores of all the members ofthe group. A note was also made of the incidence of gingivitis on theadjacent gum line.

For further comparison purposes, the procedure of the set out above inthis example was repeated in a separate set trial, with the exceptionthat, instead of being fed the product of the present invention, thedogs in the original first group (“Product 1”) were fed commercial dogbiscuits in an equivalent quantity (i.e. at ˜25% of dietary MErequirements). The results of this trial are reported in table 4 withthe designation “Biscuit 2” for the group of dogs (formerly group“Product 1”) receiving the commercial dog biscuit as a chew, and“Control 2” for the group receiving only commercial canned petfood.

The results in tables 4 and 5 show that the product of the presentinvention is significantly effective in reducing tartar on dogs' teethwhen compared to the control and even to competing biscuits. It isespecially effective in reducing the formation of tartar in the rearteeth when compared with the products claimed by their manufacturers toreduce tartar, such as the biscuit in the Biscuit 2 diet.

For the animals fed the “Product 1” diet, a small but significantreduction in the incidence of inflammation for the gum area adjacent tothe rear teeth and in particular adjacent to premolar 3, the mostcommonly extracted tooth for many dog breeds, was observed.

TABLE 4 Mean Group Tartar Scores All Upper Jaw, PM3, Front Diet TeethPrimary Molars PM4 & M1* Teeth Product 1 2.96 3.38 3.67 2.3 Control 16.05 11.21 10.05 2.2 Biscuit 2 3.97 3.78 6.30 3.15 Control 2 5.84 7.309.23 3.46 *3^(rd) Premolars; 4^(th) premolars and first molars.

TABLE 5 Percentage Tartar Reduction when diet is supplemented with chewproducts All Upper Jaw, PM3, Front Diet Teeth Primary Molars PM4 & M1*Teeth Product 1 51% 70% 63% 0%** Biscuit 2 32% 48% 32% 0%** **Nosignificant difference

EXAMPLE NO. 3

In a separate test, the digestibility of the product of this inventionwas tested. Eight adult beagle dogs (4 female, 4 male) in good healthwere individually housed and fed once a day with a test diet.

This test group was designated “Product ID” and the dogs were fed a testdiet that was a combination of the product of this invention and acommercial canned petfood available under the trade name “Winalot”(Winalot is a trademark of Societédes Produits Nestlé, Vevey,Switzerland). These foods were the only the sole source of nutrition forthe animals during the trial. The daily ration was calculated for eachanimal based on its daily metabolic energy (ME) requirement. This wascalculated using the formula:ME requirement=132×BW ^(0.75)

The product was sent for analysis before the test started and analysedfor moisture, protein, fat, ash, fiber and gross energy. The ME of theproduct was calculated using the formula:ME of product=(3.5×% protein)+(8.5×% fat)+(3.5×% carbohydrate).

The diet was a combination of the canned commercial petfood, at 75% ofthe daily metabolic energy requirement, and the product of thisinvention manufactured according to example 1, at 25% of the dailymetabolic energy (NE) requirement. Fresh water was provided at alltimes.

Initially, all the dogs were fed for 5 days on the given diet. Thisallowed them to adapt to the diet. After 5 days, the weight of each dogwas measured to calculate its ration for a stool collection phase tofollow. During the collection phase, the dogs were continued on the samediet for a further 5 days, during which the feces were collected.

On the first day of this phase, each dog was given 1 g of iron oxidemarker mixed into the food. This indicated the start of the fecalcollection (The first feces collected were red). During the remaining 4days the food was given as normal. The day after the finish of the 5 daycollection phase period, red iron oxide was again given (1 g) mixed intothe food to mark the end of the fecal collection. (These red feces werenot collected).

Daily food intakes and fecal score were recorded. After daily collectionof the feces, they were stored in a freezer at −20° C. The feces foreach dog was pooled for the 5 day collection period (all feces up to thefinal red marker). The total wet weight of the feces was recorded. Alldogs were reweighed at the end of the trial.

The feces were dried in a freeze dryer. The total quantity of feces wasdried, after thorough mixing. The weight of the dried feces wasrecorded. The dried feces were ground and sent for analysis formoisture, protein, oil, ash and gross energy (GE).

The digestibility was calculated using standard AAFCO methodology,where:${{Dry}\quad{Matter}\quad{Digestibility}},{{({DMD})\quad\%} = {\frac{{g\quad{of}\quad{DM}\quad{consumed}} - {g\quad{of}\quad{DM}\quad{in}\quad{faeces}}}{g\quad{of}\quad{dry}\quad{matter}\quad{consumed}} \times 100}}$(where  ″g″  represents  mass  in  grams)${{Protein}\quad{Digestibility}},{{{PD}\quad\%} = {\frac{{g\quad{of}\quad{protein}\quad{consumed}} - {g\quad{of}\quad{protein}\quad{in}\quad{faeces}}}{g\quad{of}\quad{protein}\quad{consumed}} \times 100}}$${{Fat}\quad{Digestibility}},{{{FD}\quad\%} = {\frac{{g\quad{of}\quad{fat}\quad{consumed}} - {g\quad{of}\quad{fat}\quad{in}\quad{faeces}}}{g\quad{of}\quad{fat}\quad{consumed}} \times 100}}$${{Energy}\quad{Digestibility}},{{{ED}\quad\%} = {\frac{{{kcal}\quad{of}\quad{GE}\quad{consumed}} - {{kcal}\quad{of}\quad{GE}\quad{in}\quad{faeces}}}{{kcal}\quad{of}\quad{GE}\quad{consumed}} \times 100}}$

-   Carbohydrate Digestibility (by difference), CD %=similar calculation    to that for protein-   Ash Digestibility, AD %=similar calculation to that for protein    ME of Product:-   ME in kcal/g=[kcal of GE consumed−kcal of GE in feces−((g of protein    consumed.−g of protein in feces.)×1.25)]/g of food consumed

Results Recorded During Collection Week: Average Range Food Intake g/day1110  941.0 to 1271.0 kcal/day 1643 1392.7 to 1881.1 BW Change % 0.22−3.35 to 3.42  

Stool Consistency Average Dogs Contributing Normal %1 86  8 Soft ButFormed %2 5 3 Unformed %3 9 3 Puddle %4 0 0 Average Range Stool Score1.23 Output - g/day 132.9  87.0 to 166.2 % moisture 71.9 65.4 to 78.7 gdef./1000 kcal ing. 81.3  54.1 to 102.8

Analysis Results Average Nutrient Content Food Feces Moisture % 82.0771.9 Protein % 5.79 9.0 Fat % 3.18 0.8 Ash % 2.98 13.4 Crude fiber %0.20 ** Carbohydrate w/out CF % 5.78 4.82 Gross Energy kcal/100 g 88.979.9 Apparent Digestibility Average Range Dry Matter % 90.4 88.0 to 93.2Protein % 92.2 90.0 to 94.8 Fat % 96.1 93.4 to 97.4 Ash % 41.4 25.9 to61.2 Energy % 94.5 93.0 to 96.1 Carbohydrates % 96.4 95.2 to 97.4Metabolisable Energy:  1.48 (kcal/g): NB. Carbohydrates value wascalculated from the analysis results of the other nutrients.

Average intakes were satisfactory and sufficient to maintain bodyweightduring the trial. Due to the high digestibility of the products theaverage actual daily intake was above the theoretical, namely 1643kcal/day versus that normally observed for the canned pet food alone of1030 kcal/day.

The fecal quality was satisfactory with 91% of the feces scored asacceptable. No liquid diarrhea was observed. The apparent digestibilityof the products was high with average values of: 90.4% (dry matter),92.2% (protein), 94.5% (energy) and 96.1% (fat).

The mixed diet of 75% canned commercial pet food (Winalot) and 25% ofthe product of this invention were as digestible, if not more so, thanthe canned commercial pet food (Winalot) when fed solely. The calculatedME from the digestibility results, corrected for urinary nitrogen losswas 1.48 kcal/g.

EXAMPLE NO. 4

In a separate test, ten dogs were provided with the product sample 1a ofexample 1. Their eating behavior was videotaped. The dogs ranged in sizeand species from French hunting dogs, through beagles to fox terriers.The product was offered directly to each dog. The dogs all took theproduct in their mouths then lay down on their stomachs and transferredthe product to their front paws. All the dogs held the product with easein a slightly inclined vertical manner, then started chewing. Carefulobservation showed that the product fitted snugly between their cheekand the molars and premolars.

For all, the primary chewing action was a munching with their backteeth. It was noticed that periodically the dogs would stop and movetheir paws slightly and then resume chewing. On 2 out of 3 occasionsthis resulted in the product reversing to the opposite side of theperpendicular, which meant the dog then resumed chewing on the oppositeside of the mouth. When having finally gnawed down to the end piece, thedogs picked the product up with their front teeth, biting and chewing anumber of times before swallowing the product. This behavior pattern wasconsistent for all dogs and was in contrast to that which was observedfor a commercially available synthetic chew product, Denta Rask(available from Pedigree Masterfoods, Melton Mowbray, UK).

A similar trial was conducted with the same ten dogs whose behavior wasagain videotaped. This time, each dog was handed one Denta Rask,weighing 64 g. It was bigger than the product made according to example1, which, in this trial, weighed 50 g. The Denta Rask was taken in itsmouth by each dog, held in the jaws and cracked into pieces with thefront teeth. The pieces were then taken and chewed.

Careful observation revealed that the dogs tend to chew Denta Rask morewith the front and center of their mouth whilst periodically pausing tocrack the product and break it into smaller pieces. The rear cheeks wereseen to bulge less often with Rask. The dogs dropped more crumbs whenchewing it. Also some dogs took substantially less time to chew DentaRask. For the 50 g product of this invention, chewing times in excess of12 minutes were observed for some beagles. In comparison, these dogschewed a 65 g Denta Rask for about 5 minutes.

This demonstrates that the product of this invention was superior inencouraging dogs to masticate with their rear teeth than some the DentaRask product of the prior art. It also shows that effective dentalhygiene products can combine product design with appropriate chemistryand texture that results from properly controlled manufacturing methods.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its intended advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

1. A chewable product capable of enhancing dental hygiene in a pet,comprising a body having a continuous phase and a discontinuous phasethat are so constructed and arranged that a force required to penetratethe chewable product is greater than an anticipated bite force expectedto be exerted by the pet during a normal biting event wherein thediscontinuous phase is composed of compositions meeting one of acriteria selected from the group consisting of:micro-occlusions/microscopic parties of all non-reactive/insolubleorganic/biological substances with melting points and/or glasstransition points above room temperature and as well those with meltingand/or glass transition points below room temperature that are notsoluble in the continuous phase; occlusions/particles of allnon-reactive/insoluble organic/biological substances with melting pointsand/or glass transition points above room temperature and as well thosewith melting and/or glass transition points below room temperature thatare not soluble in the continuous phase; non-active inorganic substancesthat are compatible with and do not react or significantly interact withthe substances present in the continuous phase; carbohydrates and/orderivatives of carbohydrates including saccharides, sugars,polysaccharides, starches; derivatives of starches, inulin,polyfructans, polydextrans; polymers of naturally occurring hexose,pentose and heptose sugars and their derivatives; cellulose and polymersderived from cellulose; amino-polysaceharides and polymers derived fromthem; oligiosaccharides, polysaceharides of and derivatives ofpolysaccharides of microbial origin; polyols; sugar alcohols, polymersof sugar alcohols, mineral oxides, inorganic and organic oxides,phosphates, sulphates, carbonates; other insoluble salts or covalentlybonded inorganic substances; polymers of or mixtures/complexes andcombinations of all of the aforementioned inorganic and organicsubstances; aluminosilicates, silicates, inorganic substances common insoils, clays, minerals, metals and substances derived from metals, bone,cartilage, oils, fats, gases, petroleum derivatives and petroleum basedpolymers; micro-occlusions/particles of microbial origin, intactnon-viable microbes, dry intact non-viable microbes, the shells and cellwall material derived from dead microbes, material of microbial origin,micro-occlusions/particles of plant origin, material of plant origin,micro-occlusions/particles of animal origin, material of animal origin;such polymers and substances of biological origin as are present ascomponents of both the continuous phase and the discontinuous phase,being present in the discontinuous phase in a different state to theirstate in the continuous phase.
 2. The chewable product of claim 1wherein the polymers and substances of biological origin are present inthe discontinuous phase predominately in a glassy or crystalline state.3. A method for making a chewable product for enhancing dental hygieneof a pet comprising the steps of: producing a chewable, edible productthat includes a continuous and a discontinuous phase; and selecting therelationship of the continuous to discontinuous phase so that the forcerequired to penetrate the chewable product is greater than ananticipated bite force expected to be exerted by the pet during a normalbiting event, enabling the chewable product after an initial bite, tospring back to at least almost its original shape wherein thediscontinuous phase is composed of a composition that meets a criteriaselected from the group consisting of: micro-occlusions/microscopicparticles of all non-reactive/insoluble organic/biological substanceswith melting points and/or glass transition points above roomtemperature and as well those with melting and/or glass transitionpoints below room temperature that are not soluble in the continuousphase, occlusions/particles of all non-reactive/insolubleorganic/biological substances with melting points and/or glasstransition points above room temperature and as well those with meltingand/or glass transition points below room temperature that are notsoluble in the continuous phase, non-active inorganic substances thatare compatible with and do not react or significantly interact with thesubstances present in the continuous phase, carbohydrates and/orderivatives of carbohydrates including saccharides; sugars,polysaccharides, starches; derivatives of starches, inulin,polyfructans, polydextrans; polymers of the naturally occurring hexose,pentose and heptose sugars and their derivatives, cellulose and polymersderived from cellulose, amino-polysaccharides and polymers derived fromthem, oligiosaccharides, polysaccharides of and derivatives ofpolysaccharides of microbial origin, polyols, sugar alcohols, polymersof sugar alcohols, mineral oxides, inorganic and organic oxides,phosphates, sulphates, carbonates; other insoluble salts or covalentlybonded inorganic substances; polymers of or mixtures/complexes andcombinations of all of the aforementioned inorganic and organicsubstances, aluminosilicates, silicates, inorganic substances common insoils, clays, minerals, metals and substances derived from the metals,bone, cartilage, oils, fats, gases, petroleum derivatives and petroleumbased polymers, micro-occlusions/particles of microbial origin, intactnon-viable microbes, dry intact non-viable microbes, the shells and cellwall material derived from dead microbes, material of microbial origin,micro-occlusions/particles of plant origin, material of plant origin,micro-occlusions/particles of animal origin, material of animal origin;such polymers and substances of biological origin as are present ascomponents of both the continuous phase and the discontinuous phase,being present in the discontinuous phase in a different state to theirstate in the continuous phase.
 4. The method of claim 3 wherein thepolymers and substances of biological origin that are also present ascomponents of both the continuous phase and the discontinuous phase, arepresent in the discontinuous phase predominately in the glassy orcrystalline state.
 5. A chewable product capable of enhancing dentalhygiene in a pet, comprising a body having a continuous phase includinga biological material and a discontinuous phase that are so constructedand arranged that a force required to penetrate the chewable product isgreater than an anticipated bite force expected to be exerted by the petduring a normal biting event wherein the discontinuous phase is composedof compositions meeting one of a criteria selected from the groupconsisting of: micro-occlusions/microscopic parties of allnon-reactive/insoluble organic/biological substances with melting pointsand/or glass transition points above room temperature and as well thosewith melting and/or glass transition points below room temperature thatare not soluble in the continuous phase; occlusions/particles of allnon-reactive/insoluble organic/biological substances with melting pointsand/or glass transition points above room temperature and as well thosewith melting and/or glass transition points below room temperature thatare not soluble in the continuous phase; non-active inorganic substancesthat are compatible with and do not react or significantly interact withthe substances present in the continuous phase; carbohydrates and/orderivatives of carbohydrates including saccharides, sugars,polysaccharides, starches; derivatives of starches, inulin,polyfructans, polydextrans; polymers of naturally occurring hexose,pentose and heptose sugars and their derivatives; cellulose and polymersderived from cellulose; amino-polysaccharides and polymers derived fromthem; oligiosaccharides, polysaccharides of and derivatives ofpolysaccharides of microbial origin; polyols; sugar alcohols, polymersof sugar alcohols, mineral oxides, inorganic and organic oxides,phosphates, sulphates, carbonates; other insoluble salts or covalentlybonded inorganic substances; polymers of or mixtures/complexes andcombinations of all of the aforementioned inorganic and organicsubstances; aluminosilicates, silicates, inorganic substances common insoils, clays, minerals, metals and substances derived from metals, bone,cartilage, oils, fats, gases, petroleum derivatives and petroleum basedpolymers; micro-occlusions/particles of microbial origin, intactnon-viable microbes, dry intact non-viable microbes, the shells and cellwall material derived from dead microbes, material of microbial origin,micro-occlusions/particles of plant origin, material of plant origin,micro-occlusions/particles of animal origin, material of animal origin;such polymers and substances of biological origin as are present ascomponents of both the continuous phase and the discontinuous phase,being present in the discontinuous phase in a different state to theirstate in the continuous phase.
 6. The chewable product of claim 5wherein the polymers and substances of biological origin are present inthe discontinuous phase predominately in a glassy or crystalline state.7. A method for making a chewable product for enhancing dental hygieneof a pet comprising the steps of: producing a chewable, edible productthat includes a continuous phase including a biological material and adiscontinuous phase; and selecting the relationship of the continuous todiscontinuous phase so that the force required to penetrate the chewableproduct is greater than an anticipated bite force expected to be exertedby the pet during a normal biting event, enabling the chewable productafter an initial bite, to spring back to at least almost its originalshape wherein the discontinuous phase is composed of a composition thatmeets a criteria selected from the group consisting of:micro-occlusions/microscopic particles of all non-reactive/insolubleorganic/biological substances with melting points and/or glasstransition points above room temperature and as well those with meltingand/or glass transition points below room temperature that are notsoluble in the continuous phase, occlusions/particles of allnon-reactive/insoluble organic/biological substances with melting pointsand/or glass transition points above room temperature and as well thosewith melting and/or glass transition points below room temperature thatare not soluble in the continuous phase, non-active inorganic substancesthat are compatible with and do not react or significantly interact withthe substances present in the continuous phase, carbohydrates and/orderivatives of carbohydrates including saccharides; sugars,polysaccharides, starches; derivatives of starches, inulin,polyfructans, polydextrans; polymers of the naturally occurring hexose,pentose and heptose sugars and their derivatives, cellulose and polymersderived from cellulose, amino-polysaccharides and polymers derived fromthem, oligiosaccharides, polysaccharides of and derivatives ofpolysaccharides of microbial origin, polyols, sugar alcohols, polymersof sugar alcohols, mineral oxides, inorganic and organic oxides,phosphates, sulphates, carbonates; other insoluble salts or covalentlybonded inorganic substances; polymers of or mixtures/complexes andcombinations of all of the aforementioned inorganic and organicsubstances, aluminosilicates, silicates, inorganic substances common insoils, clays, minerals, metals and substances derived from the metals,bone, cartilage, oils, fats, gases, petroleum derivatives and petroleumbased polymers, micro-occlusions/particles of microbial origin, intactnon-viable microbes, dry intact non-viable microbes, the shells and cellwall material derived from dead microbes, material of microbial origin,micro-occlusions/particles of plant origin, material of plant origin,micro-occlusions/particles of animal origin, material of animal origin;such polymers and substances of biological origin as are present ascomponents of both the continuous phase and the discontinuous phase,being present in the discontinuous phase in a different state to theirstate in the continuous phase.
 8. The method of claim 7 wherein thepolymers and substances of biological origin that are also present ascomponents of both the continuous phase and the discontinuous phase, arepresent in the discontinuous phase predominately in the glassy orcrystalline state.